Biology subjects

Darrasse-Jeze, G.

Publications and source records attributed to Darrasse-Jeze, G..

4 recordsLinked to original sources

bioRxiv2026

Toll-like receptor 9 contributes in microglial activation and lysosomal dysfunction to promote Alzheimer disease

Toll like receptor 9 (TLR9) is an endosomal-lysosomal innate immune receptor which recognizes microbial and host-derived double-stranded DNA (dsDNA) to induce cellular immunity. TLR9 pathway has been implicated in Alzheimers disease (AD) pathology via its ability to modulate peripheral immune cells but its exact role in the central nervous system (CNS) remains unclear. Here we show that extranuclear dsDNA accumulating in human AD brain and in a mouse model of AD, together with microglia around amyloid-{beta} (A{beta}) plaques stimulates TLR9 in vitro. Loss of TLR9 inhibits the transition of homeostatic microglia to reactive microglia, a cell type associated with a chronic pro-inflammatory state, promoting their reprogramming into an anti-inflammatory state, thereby restoring lysosomal integrity required for A{beta} peptides degradation. Predisposition to lysosome permeabilization could be mimicked with repeated TLR9 stimulation using CpG-A ODNs in a human microglial cell line and was rescued with TLR9 inhibition. Furthermore, lack of TLR9 protects mice developing AD from cognitive defects and neuronal loss. A{beta} pathology is also reduced specifically in male mice. Altogether, our results have identified a critical role of TLR9 in AD, where it modulates microglial activation and lysosome function to interfere with the progression of AD. These findings suggest that targeting TLR9 signaling and lysosomal function may be a relevant strategic approach to reduce AD pathology.

immunology↗

bioRxiv2024

Application of the AMOCATI R workflow to tumor transcriptomic data delineates the adverse effect of immune cell infiltration in immune-privileged organs

Immune cells are present inside tumor tissue and can alter tumor growth. Expression profiles of human tumors hold transcripts from cancer cells and their microenvironment, including the infiltrating immune cells. Few standardized methods examine tumor immunobiology relying only on tumor transcriptome data. Using a new in-house developed R analysis workflow called AMOCATI, we classified 43 cancer types from 11,176 patients according to the degree of infiltration by 18 distinct immune cell subsets, measured by the abundance of their transcriptomic signature, and calculated its effect on the disease outcome. In about half of cancers affecting organs without immune privilege, immune cell infiltration has beneficial effects. In contrast, immune infiltration in cancers of immune-privileged organs (eye, testis and brain) confers poor prognosis. Moreover, transcriptional evidence of increased immune cell activity in immune-privileged cancer sites is associated with bad prognosis. Thus, our results suggest that the effect of immune infiltration may depend on the origin of the primary tumor. SIGNIFICANCEOur in-house developed computational R approach AMOCATI allows to easily download public transcriptomic and clinical data, classify and analyze them. AMOCATI permitted us to define gene expression signatures associated with short- or long-term survival from 11,176 untreated patient unsorted biopsies in 43 types of cancer. We present the level of infiltration of 18 types of immune cell subsets transcriptomic signatures and 50 immune-related pathways in all these cancers Correlation between immune infiltration of the tumor and survival establishes a link between tumor tissue of origin and the overall effect of immune infiltration on survival. Immune cell infiltration in tumors from immune privileged organs correlate with shorter survival. Contrary to what we observe in hot tumors, biological pathways of immune response are associated with a short-term survival profile in these cancers.

cancer biology↗

bioRxiv2023

Tissue-resident uterine regulatory T cells support fetal growth

Regulatory T cells (Tregs) are known to contribute to successful allogeneic pregnancy by promoting maternal-fetal tolerance. Here, phenotypic studies and parabionts identified a population of uterine tissue-resident Tregs (uTregs) with trophic functions in the non-pregnant mouse endometrium. Phenotypically, uTregs are CD25-/lo and they present characteristic phenotypic attributes of tissue-resident memory T cells with effector functions. Transcriptionally, uTregs are distinguishable from other peripheral or tissue-resident Tregs by their expression of genes related to extracellular matrix remodeling and vasculogenesis, and they express a polyclonal T cell receptor (TCR) repertoire. Pregnancy triggers the expansion of uTregs, which remain CD25-/lo, retain their polyclonal TCR repertoire, and increase the expression of genes involved in regulation of hypoxia and vasculogenesis. Functionally, we show that uTregs support the proliferation of primary uterine microvascular endothelial cells in vitro and that a specific depletion of uTregs in pregnant mice leads to fetal intra-uterine growth retardation (IUGR). Thus, a previously unidentified population of CD25-/lo uTregs promotes uterine tissue remodeling before and during pregnancy, and contributes to fetal growth.

immunology↗

bioRxiv2016

An evolving cancer instigates clonally unrelated neighboring cells to form distant metastases.

Based on the clonal evolution theory of cancer formation, a single cell within a tissue gains a cancer-driving mutation and thus a growth advantage. From this expanded cellular mass, another cell gains a new mutation allowing this newly mutated cell to gain new competitive advantage and to expand in number (thus clonal expansion). Another clone then emerges. Eventually all required mutations are gained, and a cancer forms. Consequently, while a primary lesion may harbor divergent subclones, all the subclones within the primary cancer as well as all metastatic growths in secondary organs share at least the very first oncogenic mutation that initiates the primary cancer. However, by tracking genetically marked mammary epithelial cells that suffered the initiating oncogenic mutation--and their neighboring mammary cells that did not-in several mouse models of human breast cancer, we found that genetically unrelated mammary epithelial cells can be colluded by neighboring mutated cells to disseminate, and that they can even undergo de novo tumorigenic transformation and form distant metastases. Therefore, clonally unrelated epithelial cells may contribute to cancer progression and to the heterogeneity of the systemic disease. The non-linear cancer spread has important implications in cancer prevention, treatment, and therapeutic resistance.

cancer biology↗